MULTITUBULAR REACTOR FOR LIQUID PHASE ALCOHOL DEHYDROGENATION AND METHOD FOR LIQUID PHASE ALCOHOL DEHYDROGENATION

Abstract

The invention relates to a multitubular reactor for dehydrogenation of liquid phase alcohol dehydrogenation and a method of liquid phase alcohol dehydrogenation. Most of the alcohol dehydrogenation reaction is endothermic reaction, the reaction temperature is high and the equilibrium conversion rate is low.

Claims

1-10. (canceled)

11. A multitubular reactor for liquid phase alcohol dehydrogenation, comprising: a reactor shell; a plurality of tubes spaced within the reactor shell, wherein the tubes are made of a gas selectively permeable membrane, which is permeable to hydrogen and oxygen but impermeable to liquid molecules, and wherein one end of the tubes is a liquid phase alcohol inlet, and another end of the tubes is a dehydrogenation product outlet; a dehydrogenation catalyst being provided inside the tubes; an oxidation catalyst being provided outside the tubes and in the reactor shell; at least one oxygen membrane tube disposed in the reactor shell, wherein one end of the oxygen membrane tube is an oxygen inlet, and another end of the oxygen membrane tube is closed; and an oxidation product outlet disposed on the reactor shell.

12. The multitubular reactor for liquid phase alcohol dehydrogenation of claim 11, wherein the gas selectively permeable membrane is made of a molecular sieve, silica, carbon, ceramics, porous stainless steel or a composite formed by two or more thereof.

13. The multitubular reactor for liquid phase alcohol dehydrogenation of claim 11, wherein the dehydrogenation catalyst is filled in the form of particles within the tubes, and the dehydrogenation catalyst comprises: a supported noble metal and a support thereof, wherein the noble metal is Pd, Pt, Ru or Au, and the support is a metal oxide, a molecular sieve, a carbon material or an organic polymer; and a non-noble metal, wherein the non-noble metal is Cu, Zn, Mn, Ni, Co, Cr or V.

14. The multitubular reactor for liquid phase alcohol dehydrogenation of claim 12, wherein the dehydrogenation catalyst is filled in the form of particles within the tubes, and the dehydrogenation catalyst comprises: a supported noble metal and a support thereof, wherein the noble metal is Pd, Pt, Ru or Au, and the support is a metal oxide, a molecular sieve, a carbon material or an organic polymer; and a non-noble metal, wherein the non-noble metal is Cu, Zn, Mn, Ni, Co, Cr or V.

15. The multitubular reactor for liquid phase alcohol dehydrogenation of claim 11, wherein the position of oxygen membrane tube is selected such that the oxidation side heating value is matched with the dehydrogenation side endothermic value at each point within the reactor.

16. The multitubular reactor for liquid phase alcohol dehydrogenation of claim 12, wherein the position of oxygen membrane tube is selected such that the oxidation side heating value is matched with the dehydrogenation side endothermic value at each point within the reactor.

17. The multitubular reactor of claim 11, wherein the oxidation catalyst is metal platinum loaded on a porous medium, and the porous medium is a metal oxide, a molecular sieve, a carbon material or hydrotalcite.

18. The multitubular reactor of claim 12, wherein the oxidation catalyst is metal platinum loaded on a porous medium, and the porous medium is a metal oxide, a molecular sieve, a carbon material or hydrotalcite.

19. A method of applying the multitubular reactor of claim 1 to the liquid phase alcohol dehydrogenation process, comprising: introducing a pre-heated liquid phase alcohol into the liquid phase alcohol inlet of the tubes in the reactor; performing dehydrogenation reaction in the tubes; obtaining a dehydrogenation product from the dehydrogenation product outlet; feeding oxygen at a preset feed amount or feed rate into the oxygen inlet of the oxygen membrane tube in the reactor; permeating oxygen from the inside of the oxygen membrane tube to the inside of the reactor shell; performing oxidation reaction of hydrogen with oxygen; and collecting water and unreacted hydrogen from the oxidation product outlet of the reactor shell.

20. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the liquid phase alcohol comprises an alcohol being in liquid phase at room temperature, or an alcohol being in solid phase at room temperature and soluble in a solvent, and wherein the solvent is kept stable under the action of a dehydrogenation catalyst, including benzene, toluene, xylene or p-cymene.

21. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the temperature of the oxidation reaction is controlled to be 50-100 C. higher than that of the dehydrogenation reaction.

22. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the oxygen feed amount, the oxygen feed rate or the activity of oxidation catalyst are controlled, such that the heating amount of the oxidation reaction is matched with the heat required for the dehydrogenation reaction, and the step of controlling the activity of oxidation catalyst comprises controlling the loading amount of metal platinum or doping an inert support in the catalyst.

23. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the liquid phase alcohol preheating temperature of the dehydrogenation reaction ranges from 100 C. to 450 C., the temperature of the dehydrogenation reaction ranges from 150 C. to 500 C., and the pressure ranges from 0.1 MPa to 5 MPa.

24. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the gas selectively permeable membrane is made of a molecular sieve, silica, carbon, ceramics, porous stainless steel or a composite formed by two or more thereof.

25. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the dehydrogenation catalyst is filled in the form of particles within the tubes, and the dehydrogenation catalyst comprises: a supported noble metal and a support thereof, wherein the noble metal is Pd, Pt, Ru or Au, and the support is a metal oxide, a molecular sieve, a carbon material or an organic polymer; and a non-noble metal, wherein the non-noble metal is Cu, Zn, Mn, Ni, Co, Cr or V.

26. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the position of oxygen membrane tube is selected such that the oxidation side heating value is matched with the dehydrogenation side endothermic value at each point within the reactor.

27. The method of liquid phase alcohol dehydrogenation of claim 19, wherein the oxidation catalyst is metal platinum loaded on a porous medium, and the porous medium is a metal oxide, a molecular sieve, a carbon material or hydrotalcite.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG. 1 is a structural schematic view of a multitubular membrane reactor of the invention;

[0032] FIG. 2 is a cross-sectional view of FIG. 1;

[0033] FIG. 3 is a structural schematic view of a single membrane tube in the reactor.

DESCRIPTION OF THE EMBODIMENTS

[0034] In order to illustrate in detail, the technical solutions, structural features, objects and effects of the present invention, embodiments are described in detail in connection with the accompanying drawings.

[0035] The multitubular reactor for liquid phase alcohol dehydrogenation and a using method thereof according to the present invention are given as follows:

[0036] The multitubular reactor for liquid phase alcohol dehydrogenation of the invention includes a reactor shell 1 and a plurality of tubes 2 spaced within the reactor shell. The tubes 2 are made of a gas selectively permeable membrane, and the gas selectively permeable membrane is permeable to hydrogen and oxygen but impermeable to liquid molecules. A dehydrogenation catalyst is provided inside the tubes, and an oxidation catalyst is provided outside the tubes and located in the reactor shell. A liquid phase alcohol inlet 3 is arranged at one end of the tubes, and a dehydrogenation product outlet 4 is arranged at the other end of the tubes. One or more oxygen membrane tubes 5 are provided in the reactor shell. One end of the one oxygen membrane tube 5 is an oxygen inlet, and the other end of the one oxygen membrane tube is closed. An oxidation product outlet 7 is provided at the bottom of the reactor shell.

[0037] The method for liquid phase alcohol dehydrogenation of the present invention is as follows: alcohol dehydrogenation reaction and hydrogen oxidation reaction take place on the inner side and outer side of the membrane of the tubes 2, respectively. On the dehydrogenation reaction side, an alcohol itself or an alcohol dissolved in a solvent (in the case that the alcohol is in the solid state at room temperature) is fed into a preheater for preheating until reaching a certain temperature, and then fed through the liquid phase alcohol inlet 3 of the tubes 2 into the dehydrogenation side filled with a dehydrogenation catalyst for reaction, and a target product is obtained from the dehydrogenation product outlet 4 and transported to a product region. Hydrogen generated by dehydrogenation reaction permeates the hydrogen selectively permeable membrane and enters into the reactor shell 1, where a catalyst for oxidation reaction is filled. Oxygen is fed at a preset amount from the inlet 6 into several dedicated membrane tubes 5 among the tubes, permeates the selectively permeable membrane and enters into the reactor shell 1 for oxidation reaction with hydrogen, and product water and excessive hydrogen are collected from the oxidation product outlet 7 of the reactor shell 1.

[0038] For some alcohol raw materials in need of dissolution (alcohols are in the solid state at room temperature), a solvent required for them includes one of benzene solvents, such as benzene, toluene, xylene, and p-cymene, which ensures normal operation of dehydrogenation reaction of the alcohols in the liquid phase state, and such solvent is inactive to dehydrogenation reaction under the action of dehydrogenation catalysts.

[0039] The membrane used in the membrane reactor is a multitubular membrane assembly, dehydrogenation reaction and oxidation reaction take place respectively in the tube pass and shell side of each membrane tube, and a dehydrogenation catalyst and oxidation catalyst are filled in the corresponding positions.

[0040] The catalyst for dehydrogenation reaction includes noble metals Pd, Pt, Ru and Au loaded on a support. The support including one of metal oxides, molecular sieves, carbon materials and organic polymers; or one of oxides of non-noble metals Cu, Mn, Ni, Co, Cr and V, or a combination thereof. The catalysts used are filled in the form of particles in the reaction tubes.

[0041] As dehydrogenation is implemented by liquid phase reaction, and hydrogen generated and another feed of oxygen are both in the gas phase, it is easy to select a highly permeable and highly selective membrane. The hydrogen-oxygen gas selectively permeable membrane is made of a molecular sieve, silica, carbon, ceramics, porous stainless steel or a composite formed by two or more thereof, and the selectively permeable membrane is permeable to both hydrogen and oxygen and impermeable to liquid molecules.

[0042] The number of several oxygen dedicated membrane tubes among the tubes may be one or more than one, they are made of a different material and may have different radius, as compared with other hydrogen selective membrane tubes. The position of the dedicated membrane tubes in the tubes is selected such that the oxidation side heating value is matched with the dehydrogenation side endothermic value at each point within the reactor. Further, the use of this method solves the problem that hydrogen easily reaches the explosion limit on the oxidation side.

[0043] The oxidation reaction is a gas phase reaction between hydrogen and oxygen to produce water, and the catalyst used is metal platinum loaded on one of porous media, such as a metal oxide, a molecular sieve, a carbon material and hydrotalcite. In order to well control the reaction rate of hydrogen oxidation reaction at each point within the reactor, during the catalyst preparation, the number of active sites is controlled by controlling the loading amount of metal platinum or partially filling an inert support material, thereby providing the desired catalyst activity.

[0044] By means of catalytic oxidation, the temperature of hydrogen oxidation reaction is 50-100 C. higher than that of hydrogenation reaction, thereby maintaining the driving force for heat transfer. The amount of oxygen fed into the membrane tubes is controlled and the activity of oxidation catalyst is regulated, so as to ensure matching between the heating amount on the oxidation reaction side and the reaction heat required on the dehydrogenation reaction side, thereby achieving in situ heating.

[0045] The feed stock preheating temperature of the liquid phase dehydrogenation reaction ranges from 100 C. to 450 C., the temperature of the reaction ranges from 150 C. to 500 C., and the pressure ranges from 0.1 MPa to 5 MPa.

EXAMPLE 1

[0046] In the example, the preparation of camphor by liquid phase isoborneol dehydrogenation was carried out within a membrane reactor. In the example, isoborneol, as industrial grade raw material which is a solid powder at room temperature, was first dissolved in xylene to form a 30% (by mass fraction) solution having the mass reaction space velocity of 0.5 h.sup.1, heated by a heat exchanger up to the preheating temperature of 220 C. and then fed into the tube pass of the membrane reactor for dehydrogenation reaction. A CuZnAl catalyst (GC250 type, Japanese NGC Co., Ltd.) was filled in the tube pass, and the bed temperature of any one of dehydrogenation reaction tubes was axially measured at the arranged point using a thermowell. Oxygen was fed into the oxygen dedicated membrane tubes in the center of the tubes after passing through a flow meter. Oxygen permeated the membrane and entered the shell side for oxidation with hydrogen, with the molar ratio of oxygen to isoborneol being 1:6. A supported Pt/Al.sub.2O.sub.3 oxidation catalyst which was prepared by multiple coating-impregnating method was filled in the shell side, in which the loading mass fraction of Pt was about 1%. The pressure on the dehydrogenation reaction side was 0.6 MPa and the reaction temperatures was 220 C.; The membrane used in the reactor was a silica membrane (SMS) from Sulzer Chemtech manufacturer, and the inner diameter and outer diameter of each tube were 8 mm and 14 mm, respectively; The mixture of target product camphor and solvent xylene, on the dehydrogenation side, entered the solvent recycling section for solvent recycling, and the product camphor was transported to a finished product region.

[0047] In the above example, the stabilized bed temperatures measured were shown in the following table (in the table, the numbers indicative of temperature measurement points were taken from FIG. 3):

TABLE-US-00001 temperature measurement points 1 (inlets) 2 3 4 5 (outlets) temperatures 220 218 221 220 221

[0048] The experiment results from the above example are compared to data from other currently used processes, the results are shown in the table below:

TABLE-US-00002 reaction conversion Selectivity/ catalysts temperatures/ C. rates/% % this example GC250 220 99.56 99.78 literature Zn-Ca type 295 99.20 97.00 values* catalysts literature values*: taken from patent CN1027755C, Lin Yunlong, et, al., preparation of camphor by isoborneol gas phase dehydrogenation.

[0049] From the comparison results, it can be seen that isoborneol dehydrogenation reaction using the method of this application has relatively high conversion rate and selectivity, and also has more uniform bed temperature in the axial direction due to the use of multitubular structure and in situ heating system, with simple and compact devices and high production efficiency.

EXAMPLE 2

[0050] In the example, the preparation of cyclohexanone by liquid phase cyclohexanol dehydrogenation was carried out within a membrane reactor. Cyclohexanol raw material was heated by a heat exchanger up to the preheating temperature of 220 C. and then fed into the tube pass of the membrane reactor for dehydrogenation reaction. The reaction space velocity of cyclohexanol being 1.0 h.sup.1, and a CuZn two-component catalyst DH021 (developed by Institute of Nanjing Chemicals Co., Ltd.) was filled in the tube pass, and the bed temperature of any one of dehydrogenation reaction tubes was axially measured at the arranged point using a thermowell. Oxygen was fed into the oxygen dedicated membrane tubes in the center of the tubes after passing through a flow meter, oxygen permeated the membrane and entered the shell side for oxidation with hydrogen, with the molar ratio of oxygen to cyclohexanol being 1:8. A supported Pt/Al.sub.2O.sub.3 oxidation catalyst which was prepared by multiple coating-impregnating method was filled on the shell side, in which the loading mass fraction of Pt was about 1%. The pressure on the dehydrogenation reaction side was 0.5 MPa and the reaction temperatures was 220 C. The membrane used in the reactor was a silica membrane (SMS) from Sulzer Chemtech manufacturer, and the inner diameter and outer diameter of each tube were 8 mm and 14 mm, respectively. The reaction product cyclohexanone was transported to a finished product region.

[0051] In this example, the temperatures measured at each point of the stabilized bed and literature values were shown in the following table (in the table, the numbers indicative of temperature measurement points were taken from FIG. 3):

TABLE-US-00003 temperature measurement points preset 1 5 values inlets 2 3 4 outlets this example/ C. 220 220 218 220 220 222 literature values*/ C. 240 237 242 240 240 242 literature values*: taken from the document: Stability comparison of two cyclohexanol dehydrogenation catalysts, Zhou Xiaoweng, et, al.

[0052] The experiment results from the example are compared to data from other processes currently used in industry, and the results are listed in table below:

TABLE-US-00004 reaction conversion selectivity/ catalysts temperatures/ C. rates/% % this example DH021 220 90.26 99.56 literature values DH021 230 55.50 99.33 1* literature values GC250 230 47.77 99.01 2** literature values LYT-96 230 52.40 99.98 3* literature values 1 and 2*: data from Nanjing DSM Dongfang Chemicals Co., Ltd.; literature values 3*: data from Hunan Yingshan Petrochemicals Plant; all from the document: Comparison of several cyclohexanol dehydrogenation catalysts, Sun Feng, et, al.

[0053] From the comparison results above, it can be seen that cyclohexanol dehydrogenation reaction using the method of this application has relatively high conversion rate and selectivity, and also has more uniform bed temperature in the axial direction due to the use of tubular structure and in situ heating system, with simple and compact devices and high production efficiency.